#include <opencv2/opencv.hpp>
#include <iostream>

int main(int argc, char** argv){
    cv::namedWindow("Example2_10", cv::WINDOW_AUTOSIZE);

    cv::VideoCapture cap;
    if(argc==1){
        cap.open(0);
    }else{
        cap.open(argv[1]);
    }
    if(!cap.isOpened()){
        std::cerr<<"Couldn't open capture."<<std::endl;
        return -1;
    }
}